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Q: I have little black gas smoke in my muffler

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I have little black gas smoke in my muffler. Why?

My car has 320000 miles.
My car has an automatic transmission.

Hi, thanks for writing in. Black smoke coming from the exhaust is usually an indication of a rich fuel condition. When this happens, this can be the result of many things such as faulty fuel injectors, a failing mass air flow sensor or a faulty fuel pressure regulator allowing too much fuel to be supplied to the combustion chamber to be burnt. When this happens the result is an excess amount of unburnt fuel being passed through the exhaust coming out in the form of black smoke. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make or suggest any repairs as needed.

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